There are a number of medicament delivery devices on the market that are capable of automatically or semi-automatically delivering doses of medicament. Such devices are constructed with a variety of inter-acting components for obtaining the desired functions, such as delivery of a medicament and after delivery lock out to prevent accidental needle sticks.
One type of such known delivery devices is an injector capable of delivering a fixed dose of medicament from a pre-filled syringe, having functions such as penetration of the patient's skin and a subsequent injection of medicament. One such particular device for example is disclosed in the U.S. Pat. No. 8,414,533, comprising an activation mechanism in the form of a button placed at its distal end. The button may only activate the mechanism if the front end of the device is pressed against an injection site. When the front end is pressed against the injection site and the button is pressed, the penetration mechanism inside the injector is released whereby the needle is pushed into the body of the patient. After this, the injection is performed. When the injection is completed, the patient withdraws the injector with the needle from the injection site, whereby a needle shield is pushed forward until it surrounds the needle and is then locked.
With an injector of the type described above, i.e., a so-called auto-injector, a pre-tensioned biasing element, typically a spring, is one of the components installed during manufacture and assembly of the device. This pre-tensioned or loaded biasing element provides the driving force to deliver the medicament when the user activates or fires the injector when placed on the injection site. Because of the pre-tensioned biasing member, there is a need to prevent, prior to the intended use of the injector, a premature firing or activation of the injector. In other words, during shipping and handling before the device is placed on the intended injection site it would be highly undesirable if the injector accidentally fired. Accordingly, manufacturers and distributors of these so-called auto-injectors have sought to develop and provide fail safe solutions or other safety solutions to prevent premature activation of the devices prior to the intended use.
Although some solutions to the above stated problems have been tried, there is still room for improvements. As presented in this disclosure, a new and improved tubular cover or needle shield is presented that solves the problem with a positive locking feature to prevent premature activation of a medical delivery device.